Paul Berry
83bea5cfbb
The order of operations for type inference of a generic invocation is now: 1. Create some constraints on type parameters by trying to match the return type of the invocation target as a subtype of the incoming type context. (For a constructor invocation, the return type of the invocation target is considered the raw uninstantiated type of the class enclosing the constructor declaration.) 2. Downwards inference: partially solve the set of type constraints accumulated in step 1, to produce a preliminary mapping of type parameters to type schemas. 3. Recursively infer all arguments to the invocation, except that if experimental feature `inference-update-1` is enabled, skip any arguments that are function literals (a.k.a. "closures"). Obtain the type contexts for the recursive inference by substituting the preliminary mapping (from step 2) into the corresponding parameter types of the invocation target. For each argument that is recursively inferred, create additional constraints on type parameters using the resulting static type. 4. If no arguments were skipped during step 3, go to step 7 (this always happens if `inference-update-1` is disabled). 5. Horizontal inference: partially solve the set of type constraints accumulated so far, to produce an updated preliminary mapping of type parameters to type schemas. 6. Recursively infer all of the invocation arguments that were previously skipped. As in step 3, obtain the type contexts for the recursive inference by substituting the preliminary mapping (this time from step 5) into the corresponding parameter types of the invocation target. Again, for each argument that is recursively inferred, create additional constraints on type parameters using the resulting static type. 7. Upwards inference: solve the set of type constraints accumulated so far, to produce a final mapping of type parameters to types. Check that each type is a subtype of the bound of its corresponding type parameter. 8. Check that the static type of each argument is assignable to the type obtained by substituting the final mapping (from step 7) into the corresponding parameter type of the invocation target. 9. Finally, obtain the static type of the invocation by substituting the final mapping (from step 7) into the return type of the invocation target. This addresses simpler cases of https://github.com/dart-lang/language/issues/731. Note that if experimental flag `inference-update-1` is disabled, the behavior is unchanged. Note that steps 2 and 5 use the same algorithm as each other (they only differ in how many type constraints have been accumulated so far), so I've renamed the function that performs it from `downwardsInfer` to `partialInfer`. Change-Id: I10d3288d4f4ba9e2b6bc18409186ddc67ca2ee9d Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/238881 Reviewed-by: Samuel Rawlins <srawlins@google.com> Commit-Queue: Paul Berry <paulberry@google.com>
Analyzer for Dart
This package provides a library that performs static analysis of Dart code. It is useful for tool integration and embedding.
End-users should use the dart analyze command-line tool to analyze their Dart code.
Integrators that want to add Dart support to their editor should use the Dart Analysis Server. The Analysis Server API Specification is available. If you are adding Dart support to an editor or IDE, please let us know by emailing our list.
Configuring the analyzer
Both dart analyze and Dart Analysis Server can be configured with an
analysis_options.yaml file (using an .analysis_options file is deprecated).
This YAML file can control which files and paths are analyzed,
which lints are applied, and more.
If you are embedding the analyzer library in your project, you are responsible for finding the analysis options file, parsing it, and configuring the analyzer.
The analysis options file should live at the root of your project (for example,
next to your pubspec.yaml). Different embedders of analyzer, such as
dart analyze or Dart Analysis Server, may choose to find the file in various
different ways. Consult their documentation to learn more.
Here is an example file that instructs the analyzer to ignore two files:
analyzer:
exclude:
- test/_data/p4/lib/lib1.dart
- test/_data/p5/p5.dart
- test/_data/bad*.dart
- test/_brokendata/**
Note that you can use globs, as defined by the glob package.
Here is an example file that enables two lint rules:
linter:
rules:
- camel_case_types
- empty_constructor_bodies
Check out all the available Dart lint rules.
You can combine the analyzer section and the linter section into a single
configuration. Here is an example:
analyzer:
exclude:
- test/_data/p4/lib/lib1.dart
linter:
rules:
- camel_case_types
For more information, see the docs for customizing static analysis.
Who uses this library?
Many tools embed this library, such as:
- dart format - a formatter for Dart code
- dart doc - a documentation generator for Dart code
- Dart Analysis Server - a stateful server that supports IDEs and editors
Support
Post issues and feature requests at https://github.com/dart-lang/sdk/issues
Questions and discussions are welcome at the Dart Analyzer Discussion Group.
Background
The APIs in this package were originally machine generated by a translator and were based on an earlier Java implementation. Several of the API's still look like their Java predecessors rather than clean Dart APIs.
In addition, there is currently no clean distinction between public and internal APIs. We plan to address this issue but doing so will, unfortunately, require a large number of breaking changes. We will try to minimize the pain this causes for our clients, but some pain is inevitable.
License
See the LICENSE file.